Two-component developer

Abstract

Disclosed is a two-component developer containing toner particles and carrier particles. The number-average particle diameter of the toner particles MDt ranges from 3.5 to 5.0 μm. The MDt of the toner particles and the volume-average particle diameter of the carrier particles MDc are at a specific ratio, and spherical fine toner particles in the toner particles and fine carrier particles in the carrier particles exist at specific percentages.

What is claimed is: 
     
       1. A two-component developer for developing an electrostatic latent image, comprising toner particles and carrier particles,
 wherein a number-average particle diameter MDt of the toner particles ranges from 3.5 to 5.0 μm, and 
 wherein the two-component developer satisfies the following Formulas 1 and 2:
   4.5≦ MDc/MDt≦ 6.5  Formula 1
 
   (2/5) X+Y≦ 20 (with the proviso that 10≦ X≦ 40)  Formula 2
 
 
 where MDc represents a volume-average particle diameter of the carrier particles, X represents a proportion (%) of the toner particles having a number distribution-based particle diameter of 3.0 μm or more to less than 4.5 μm and a circularity of 0.980 or more in a total of the toner particles, and Y represents a proportion (%) of the carrier particles having a volume distribution-based particle diameter of (2/3)×MDc or less in a total of the carrier particles. 
 
     
     
       2. The two-component developer according to  claim 1 , wherein the two-component developer satisfies the following Formulas 3 and 4:
   5.0≦ MDc/MDt≦ 6.0  Formula 3
 
   (2/5) X+Y≦ 16 (with the proviso that 14≦ X≦ 35)  Formula 4.
 
 
     
     
       3. The two-component developer according to  claim 1 , wherein
 the toner particles include toner base particles, and 
 the toner base particles are toner base particles obtained by aggregating and fusing colorant particles and particles of a binder resin dispersed in an aqueous medium. 
 
     
     
       4. The two-component developer according to  claim 3 , wherein the binder resin includes a crystalline resin. 
     
     
       5. The two-component developer according to  claim 1 , wherein
 the toner particles further include an external additive, 
 the external additive includes silica particles produced by a sol-gel method, and 
 a number-average primary particle diameter of the silica particles is 70 to 200 nm. 
 
     
     
       6. The two-component developer according to  claim 1 , wherein
 the carrier particles each have a core material particle and a layer of a coating material that coats the surface of the core material particles, and 
 the coating material includes a resin having a cycloalkyl group.